Boiler-tube connection



` F. T. HUsToN BoILzn 'russ commc'rror v uriginal Filed Feb. 14. 1916 20 AFigure 55y as copper,

Patented Mar. 17, 1925i.

L,UNITED=fs1fnf11afs vjrPa*F'ENT-g OFFICE.

. 1nolILnn-TUBEy CONNECTION.

Appucationme February 14, 1916, serial-N0. 78,143. Renewed June 22, i922. 'seran No. 570,185.

:Tube Connections, of whiclrthe following iis a. speciiication. j

vThis invention relates tobeilerswand the process of inalring same, and has for. `its.

l-object toprovidea-new boilerand .a new process for. .electrically welding boilertubes yto the fiue sheets.

i Theinventionfis illustratedin the acconr j ,Y

-. suitable controller-14 in thecircuit. It Will drawings, whereinv Figure 1 .is ajsectionalxviewv through a aboiler tube and a` portion ofthe'itwo flue4 sheets withJthe weldingl terminaluin posi-l .tionf and before the @welding has .been comj gpletedg v 2 is a sectional view throughthe '-r end of theboilertube anda vportion of the flue-sheet after the welding-,has been completed;l

Figure 3 isan end view lof the .weldingI terminal;

i Figure 4 is a view similar to Fig. 2 showing a'modied construction, 'l

Like numerals refer to like parts throughout the several figures.

Y 3o :1 In` the, drawings I have shown one form of 3, this terminalis made up of. a plurality of l sections 4, with means for forcing .them oute u wardly so as to providethedesiredpressure between the lterminal and the inner face ofY y the tube 1; Thisis accomplished means of a steel `expander.located between :these 4.5` sections and consisting ofthe outerexpansi-y blepart 5 preferably made in sections, which engages the sections 4 and which has a tapered -hole therethrough, `there being a l tapered pin infsaid hole, which when driven in, expands the sections 4 so Vas vtoftightly press themV against the inner face of the tube 1. y y periphery with a flexible device 7, preferably made up of4 a series of strips of metal, such and through whichA the current The terminal is provided at J its ,isc'onducted to thel terminal, the iiexibility of the'device permitting the terminal to ex- .pand .hereinbefore setir out.y The flexible conducting device 7 is-'preferablylocated in a groovein the terminal and is tightly pressed against the Vterminal in any desired 'mannenv asi` by means of a spring 8.' This iiexible conducting'devicef is connected in circuit with a source4 of current supplylQ by. the 4conducting piece 9 and the conductor 10. Theother'terminal of thesource of .current supply 12 is connected yby a conduc tor, 13 .with the flue sheet 2, there being a be noted that the cross sectional areajof the ',boilerftube is less than the cross sectional ,area of the Hue sheet, and lI thereforeprovide-some means for equalizing this cross ,sectional area alt the point of lcontact,1thus permitting the' boilery tube and the flue sheet to bebroughtto substantially the same heat yat substantially the same time,'thereby insuring the' proper weld. This equalizin of the cross sectional area may be securef'in any desired manner. In the particular construction shown'I secure vit by yremoving some of the metal of the flue sheet by' providingaJ groove Qaiextending entirelytherearound, thus forming theV projections 2b, which engage the `boiler tube'. 'This constructionv also secures' an additional strengtheningetfect, as hereinafter described.` i The electrical terminal 3 is preferably arranged so-as to p ro'perly'take carfe of the heat,v thus preventing it from becoming overheated. Anyf suitable means 'for this purpose maybe used. Underlordinary conditions the terminal itself will ,be Vable to take care of Vthe heat o'naccount of its size. lI prefen however,5to provide some cooling means for this terminal. In the construction shown, I providemeans for circulating a cooling liquid through the terminal. This may be done by providing passageways 15 and 16 in the terminal, that is, in the different sections of the terminal that project into vthe boiler tube, this being thepoint wherethetgreatest heat is developed. W'Ihese pasageways are then k connected by ,otherpassageways' 17, through-which vthe 'liquid Hows to and from them. VVIn view ofthe fact that the sections of the terminal are separated froineach other, the cooling liquidmay pass in the one section itlirough the 'pipe 18, andthen pass from". said section to the next section, through.

the pipe 19, and from said latter section to the next section through the pipe 20, and

then out through the pipe 21, thus forming a circulatory system whereby the cooling liquid is circulated through the terminal. In view of the fact that pressure is applied to the terminal, I prefer to have the passageways 15 and 16 separated by a wall or ribs 22. It will thus be seen that by means of this process a practically uniform pressure is secured throughout the entire inner surface of the boiler tube, and that a practically uniform pressure is also secured between the outer face of the boiler tube and the flue sheet, thus insuring the welding of the boiler tube to the iiue sheet all the way around, and providing an absolute watertight joint. Nhen the heat is turned onand the parts are in the position shown in Fig. 2 and the metal is brought to the proper temperature, the pin 6 is driven into the expander, thus uniformly expanding the tei'- minal and also uniformly expanding the end of the boiler tube, causing it to be welded to the flue sheet. At the same time a portion of the metal is forced outwardly into the groove 2zL in the flue sheet, thus. acting as a lock to greatly strengthen the joint and prevent the two from being moved with relation to the flue sheet.

If it is desired to also weld the other ends of the boiler tubes to the other flue sheet 25,'

another electric terminal is placed in the end of the boiler tube and the current is simultaneously passed through both terminals so as to simultaneously weld both ends. Under ordinary conditions, however, it is only necessary to weld the ends of the boiler tubes nearest the fire-box, because these ends are subjected to very high temperatures, while the other ends are not subjected to these high temperatures. It is found in practice that with the method now generally used for connecting the ends of the boiler tubes with the flue sheets, the connection with the flue sheet near the fire-box is the one that gives trouble due to these high temperatures, and these ooiinections at the fire-box end require continual repairing, all of which are avoided by the present process and construction. If it is only desired to weld the ends of the boiler tubes nearest the fire-box to the flue sheet, the other ends of the tubes are provided with insulating bushings 26 (see Fig. 1), so as to confine the current to one end of the tube. After the welding has been completed these insulating bushings are rcmoved and replaced by metal bushings made of copper or other proper material, and these ends of the tubes are then rolled in the ordinary way to fasten them to the flue sheets.

In Fig. 4 I have shown the boiler tube with the end 28 rolled over so as to form a gages the other side of the iiue sheet. I prefer, however, to make the end of the boiler tube flush with the flue sheet, as shown in Fig. l, because excessive heat in the fire-box burns the end when formed into a bead, as shown in Fig. 4. The part 29 may also be omitted, because the portion of the tube which is forced into the groove 2a acts as a lock to take the strainV from the welded jointand prevent lateral movement of the tube with relation to the flue sheet. The pipes 18, 19 and 2O are arranged so as to permit the spreading out of the sections 4, and are preferably flexible pipes of any suitable construction. I also provide an insulator 4a between the sections 4 of the electric terminal and the flue sheet, which is engaged by the sections 4 when the terminal is in its maximum in position, thus acting as a stop and at the same time preventing the current from passing to the flue sheet except by way of the boiler tube. The sections t have the axial parts which enter the tube and the lateral projecting parts which engage the insulating piece 4a, a portion o-f the metal between these two parts being preferably out away as shown at 4b. This cut-away portion is particularly adapted for use when the ends of the boiler tubes are provided with beads 28.

It will be noted 'that in the present-case it is not necessary to cut away any portion of either face of the flue sheet, the flue sheet in each instance having smooth faces without cuts or recesses of any kind therein which would weaken them. And it is further noted that the weld between the boiler tube and the Hue sheet is made between these two smooth uncut or unrecessed walls of the flue sheet, and that that portion of the tube between these two walls is the portion of the tube that is expanded during the process of forming the weld.

I claim:

1. A boiler comprising a flue sheet having an opening therethrough, a boiler tube having its end projecting into said opening in said flue sheet and welded to the iiue sheet, Y

2. A. boiler comprising a flue'sheet having an opening therethrough, a boiler tube having its end extending into said opening, the flue sheet being provided with two separated projections, separated by a space, said separated projections engaging the outer face of the boiler tube and being welded to the boiler tube so as to form a tight joint, a portion of the boiler tube between said separated projections projecting into said space `iiue sheet.

but free from a welding connection with said 3. A boiler comprising a iue sheet having an opening therethrough, a boiler tube having its end extending into said opening, the flue sheet being provided with separated projections which engage said tube, and a welded joint between said projections and said tube a portion of the tube between said projections being separated from the flue sheet by an air space.

4. A boiler comprising a metal flue sheet, a metal tube extending through said flue sheet, the thickness ofjthe flue sheet being greater than the thickness of the metal of the tube, a portion of the metal of the flue sheet being removed at the point where the tube contacts with the flue sheet so as to make the thickness of the metal of the ine sheet and the tube at the point of contact substantially equal and a welded connection between the tube and the faces of the opening. having the smallest diameter.

5. A boiler comprising a metal flue sheet, a metal tube extending through said flue sheet, the thickness of the flue sheet being greater than the thickness of the metal of the tube, a portion of the metal of the Iiue sheet being removed at the point where the tube contacts with the iue sheet so as to make Vthe thickness of the metal of the flue sheet and the tube at the point of contact substantially equal and a welded joint between the iue sheet and the tube at the point of contact.

In testimony whereof, I affix my signature l in the presence of two witnesses this 22nd day of Januarly, 1916.

F EDERICK T. HUSTON. Witnesses:

ESTHER VAN FRANK, ELLA THIEME.y 

